Clinical Implications of Ultrasound-Based Morphology in Choroidal Melanoma.

Objective: To describe the frequency of different B-scan morphologies and their association with clinical features and outcomes.

Design: Cohort study of patients enrolled in the Prospective Ocular Tumor Study from January 2000 to January 2024 initially seen at Mayo Clinic Rochester.

Participants: Consecutive inclusion of patients with posterior uveal melanoma.

Methods: B-scan ultrasounds were performed by an experienced technician and treatment modalities were implemented by the attending oncologist.

Main outcomes and measures: Tumors were classified by shape as observed on B-scan. Enucleation-, metastasis, -and overall survival (EFS, MTS, and OS) rates were analyzed using Cox-regression models and Kaplan-Meier curves.

Results: Among 1021 cases of uveal melanoma, 739 (72.4%) were dome-shaped, 119 (11.7%) mushroom-shaped, 85 (8.3%) multilobulated, 77 (7.5%) minimally elevated, and 1 (0.1%) diffuse. The median follow-up duration after presentation was 37 months (3-324). The macula was more commonly involved in minimally elevated tumors compared to the other groups (63.6% vs. 13.8%, p<0.001). These tumors also exhibited a larger proportion of high internal reflectivity (13% vs. 2.3%, p<0.001). The multilobulated group exhibited a significantly larger diameter at baseline (median 15 mm, IQR 6.1-30), whereas the mushroom-shaped group had greater thickness (median 7.9 mm, IQR 1.3 - 17.3) compared to the other groups (p<0.001). EFS at 36 months was lower for mushroom-shaped [60.1% (95% CI, 47.7-70.3)] and multilobulated tumors [71.1% (95% CI, 55.7-82.7)]. At 36 months, multilobulated tumors had lower MFS [68.2% (95%, CI 55-78.2)] and OS [73.9% (95%, CI 59.9-83.64)]. On multivariate analysis adjusted for tumor thickness and diameter, multilobulated melanomas had a higher risk of metastasis (HR 2.08, p=0.003) and death (HR 2.38, p<0.001).

Conclusion: Choroidal melanoma configuration by B-scan can vary from minimally elevated to dome-shaped to mushroom-shaped or multilobulated. Independent of presenting tumor size, multilobulated morphology was identified as a predictor for metastasis and death. Multilobulated melanomas, identified by a readily available tool such as ultrasonography, warrant a vigilant approach and close monitoring due to a potential association with poor prognosis.